Abstract: A device for delivering one of a plurality of gases to an apparatus includes at least two valves. Each valve includes a first conduit permanently connected by one end thereof to an associated sampling line and, by another end thereof, to an associated purge line. Each valve includes a second conduit and an actuator which can be switched between bringing the first conduit into communication with the second conduit and a position for isolating the first conduit from the second conduit. At least the second conduit is free of flow-stagnation volumes. The second conduits of the valves are placed in series in a common gas delivery line for delivering gas to the apparatus. The end of the common gas delivery line opposite the apparatus emerges in an associated purge line. Each purge line passes through an element for creating a pressure drop. A use of the device is as a feed for trace impurities analyzer an atmospheric pressure ionization mass spectrometer or a particles analyzer.